Fresnel for LF? Need some clarity, please!

[rbiemer]

I've been thinking I want to add a fresnel lens to my focus screen for my 4x5 camera but after reading around the web, I keep seeing conflicting info about this.

My desire is to brighten the screen, the camera and my lens focus fine it is just a little dark. And I don't want to spend a ton of $ for this--it's about convenience not necessity.

Initially, I figured to just find some inexpensive fresnel and put it on the back/out side of the screen, the side facing away from the lens. This, I think, wouldn't change where the image is formed for focus and would, I thought, just increase apparent brightness.

However , after spending this morning reading about this, I am seeing lots of disagreement about the correct way to do this.

I'm a little interested in the theory about this but am much more interested in empirical/practical application.

So, who's got the straight poop on this?

Thanks!
Rob
_____

[Dan Fromm]

The straight poop is that it depends on the camera. Some have backs were made to accept a fresnel in front of the GG and have lost the fresnel. This sometimes happens with, for example, some, not all, post-1949 Pacemaker Graphics. Most backs are made without any thought of a fresnel; with them, it should go behind the GG.

The first step to a brighter GG is washing it, making sure to put it back in the focusing panel ground side facing the lens.

[rbiemer]

The straight poop is that it depends on the camera. Some have backs were made to accept a fresnel in front of the GG and have lost the fresnel. This sometimes happens with, for example, some, not all, post-1949 Pacemaker Graphics. Most backs are made without any thought of a fresnel; with them, it should go behind the GG.

The first step to a brighter GG is washing it, making sure to put it back in the focusing panel ground side facing the lens.

Dan,
Thank you for that good info!

I should have been more clear in my initial post: the camera is my 6 month old Intrepid. So, effectively new and not made to have a fresnel, just the ground glass.

Thanks!
Rob

[Dan Fromm]

I've never dealt with the Intrepid folks, but by all accounts they're quite decent. Why don't you ask them what you should do?

[JeffBradford]

If your camera already works fine without the fresnel, put the fresnel on your side of the ground glass, not the lens side.

[tom43]

You have seen this?

https://www.youtube.com/watch?v=CVpveOEk-I0&t=495s

[Qamaro]

Alan's method in the video is to apply the Fresnel to the inside of the holder (i.e. in front of the GG - Fresnel facing lens) it takes him a bit of dremel work to get the Intrepid to take it.

For an alternate look at Justin Lowery's Intrepid review (http://istillshootfilm.org/post/154811037579/intrepid-4x5-camera-review), where he affixes a Fresnel to the outside (above the GG - photographer side). You can also see a video (https://www.youtube.com/watch?v=ZBz7YhcUdGo)from Nicos Photography Show that shows him installing a Fresnel for his Chamonix 4x5 while different than an Intrepid it's mounted on the outside (just for reference).

I'm thinking of adding one myself but on-stop of the GG, Justin's method (i.e. on the outside with GG facing lens).

[mdarnton]

I would buy a cheap reading fresnel first, and mount it on top of the ground glass to see if you like the result. The purpose of a fresnel isn't to brighten the view as much as to turn the light from the edges inwards towards your eye so that the whole view is more evenly illuminated. A quick check with a $5 reader will tell you if that's something you think is an improvement. If not, then you need to search for a brighter, aftermarket ground glass ($$$). Others will have more to say about that--I've always been happy with whatever came with my cameras.